Hi Guys: I just picked up 2 trapdoors and I was wondering if someone could check the serial numbers for me. The first is a carbine #452669. There is no cartouche but I’m guessing 1889 production? It has an 1873 breech block which worries me somewhat. Shouldn’t it have an 1884 marked block? The second one is #522593 RRB. It has an 1891 cartouche and it also has an 1873 breach block. This should surely have the later one. The #522593 also has a 3/16 inch hole drilled through the front of the trigger bow. Is this something Bubba did or was it a way the Springfield Armory marked their rejects? Also, what is the meaning of the “A” that is stamped in the top of the barrel about ¾ inch in front of the receiver? Thanks to all for your help. -Tom